Use of trailers towed by various vehicles on the ground or in the water for storing and transporting goods in both domestic and industrial applications is well-known in the field. A typical trailer application may include a hitch mounted on a vehicle with a receiver for receiving a ball mount assembly and a coupler on a trailer with a socket for linking the trailer to the hitch through the ball mount assembly. When the trailer is not towed or not connected to the vehicle, it can be easily hitched up to another ball mount through the trailer's coupler front end and towed away by an unauthorized person. There is a recognized need for providing a security device such as a lock for blocking trailer coupler from being attached to a ball mount in order to prevent unauthorized removal of the trailer while the trailer is not in active use.
The above problem has been recognized in the art and various approaches have been attempted to address the issue. These include those described in U.S. Pat. No. 6,666,051, U.S. Pat. No. 6,722,686, U.S. Pat. No. 7,121,121, and U.S. Publication No 2005/0039498.
U.S. Pat. No. 6,722,686 provides a coupler lock with a removable U-shaped lock bar to engage with a lock housing having a ball-shaped dome to be attached to a trailer coupler socket so that the U-shaped lock bar is fastened over the trailer coupler to obstruct engagement between a hitch ball and the trailer couple socket. U.S. Pat. No. 6,666,051, U.S. Pat. No. 7,121,121, and U.S. Pub No. 2005/0039498 teach similar techniques of locking a trailer hitch coupler using a removable lock bar fastened to a lock housing having a ball-shaped member. Each of those devices requires the lock bar to be completely released from two apertures in the lock base in order to attach or detach the ball-shaped member to or from the coupler socket. Therefore, the lock bar may not be coupled to the lock housing when the device is not in use, which raises the issue of the lock bar being misplaced or lost.
Further as a conventional lock bar is fastened by engaging both arms in the two apertures on the lock base, alignment between the arms of the lock bar and the apertures of the lock base has to be well maintained. A slightly bent lock bar would prevent the arms from being slid through the apertures, which makes handling more difficult. And more openings and penetrations make the conventional lock base more prone to problems like blocked or rusty interior.
In addition, a conventional lock bar engaged in a lock base limits the models of trailer couplers that can be positioned over the ball-shaped member and secured by the lock bar. Trailer couplers are made with various cap sizes and/or rim sizes for trailers with different weight carrying capacity. Accordingly locking devices with different sizes of ball-shaped members and/or lock bar dimensions have to be selected for locking different models of trailer couplers. Therefore, a conventional coupler lock may not be used interchangeably on various trailer couplers that bear different cap and/or rim sizes.